1. Field of the Invention
The present invention relates to a detachable transmission mechanism for a wheel chair and a driving device in the transmission mechanism and particularly to an electric transmission mechanism for a wheel chair, with which an existing wheel chair can be attached by way of DIY (Doing It Yourself). Further, a revised driving device of the wheel chair is provided in the present invention in which a driving wheel can be rotationally moved with electric power or in a state of idling by way of a manual controller being operated to join with the driving wheel selectively.
2. Description of Related Art
The wheel chair was specially developed for handicapped or slowly moved aged persons and while a user sits in the wheel chair and pushes both lateral large wheels with both hands actuating grip rings coaxially connecting with the large wheels, the movement of the wheel chair can be obtained purposely. A weak person or a hand-hindered person resulting from illness or wound usually is unable to exert a force to the large wheels so that it is necessary to ask some other persons for gripping the handles at rear side of the wheel chair before the wheel chair can be moved. Hence, the conventional wheel chair has to be assisted by the user himself or any other person in order to meet the basic requirement of movement.
Accordingly, the so called electric wheel chair has been developed and the feature of the electric wheel chair is a transmission mechanism is provided under a xe2x80x9chxe2x80x9d shaped seat, that is, one of two rear wheels is designed as the driving wheel and the other one rear wheel is the follower wheel so as to constitute a basis of moving forward. Two front wheels are controlled by a stir stem located at the armrests being shifted to front, rear, left or right so that the wheel chair can move toward a direction desired by the user. Although the conventional wheel chair has a good and easily operated control device, there still are following deficiencies: 1) the transmission mechanism of the electric wheel chair has to be driven with the electric power and it becomes unmoved in case of the electric power is depleted and the basic function of manual drive has lost; 2) In order to obtain the effect of speed differential (that is, the inner side rear wheel has a less rotational speed than the outer side rear wheel) for the two rear wheels and to avoid turning over or a risk of being unable to turn during the wheel chair making a turn, a sophisticate speed change box has to be mounted between the two rear wheels so that it increases the complicity of the transmission mechanism of the wheel chair; and 3) due to both the body and the transmission mechanism of the conventional electric wheel chair being made with complication, the production cost thereof is pretty high so that the retail price thereof is much more expensive and is not possible to become prevalent among handicapped and motion hindered persons.
An object of the present invention is provide a detachable transmission mechanism for a wheel chair, which includes a control unit, two support frames, a suspension frame and a driving device. The channel clamps of the two support frames can be connected to two lower transverse rods of an existing wheel chair and the joining tubes at two sides of the battery unit is connected to the joining pipe so that the battery unit can be fixed beneath a seat of the wheel chair; furthermore, the control unit is positioned on one side of one of armrest of the wheel chair so that in case of the handle being rotated, the vertical shaft, rotary plate and the connecting rod can move relatively and in turn rotate the suspension frame as well as the driving device; and when a control switch is turned on, the driving wheel can be rotated in either forward or reversed direction and thus move the wheel chair forward or backward.